Booster device



1966 T. c. CERWONKA 3,

BOOSTER DEVICE Filed April 28, 1965 i194; THOMAS C CERWONKA INVENTOR.

AGENT United States Patent 3,276,372 BOOSTER DEVICE Thomas C. Cerwonlra,Kingston, N.Y., assignor to Hercules Powder Company, Wilmington, Del., acorporation of Delaware Filed Apr. 28, 1965, Ser. No. 451,510 Claims.(Cl. 102-24) This invention relates to detonator boosters and moreparticularly to an improved booster device designed to be initiated byblasting caps.

The art in respect to the use of relatively insensitive blasting agentswhich require a booster charge to obtain proper detonation is wellestablished. Frequently, it is most desirable to employ commercialelectric blasting caps as the source of initiation for the boostercharge. For so doing, a cap well is generally provided within thebooster for insertion of the blasting cap therein. It is conventionalpractice to dimple or stake the cap well so that when the cap isinserted therein, the dimple or stake serves as a restraining means toretain the cap within its well. It has been found, however, that suchrestraining means are not entirely satisfactory. This has been due to anextent to the inability to hold close tolerances during dimpling orstaking and to a further extent to the dimple or stake losing itsresiliency when rigid material such as the pressed booster charge itselfor a sealing compound such as molten sulfur or the like is placed behindthe dimple or stake. Accordingly, on one hand, the blasting cap isdifficult to insert into the cap well, and on the other, after the capis forced into the well, a certain amount of deformation has occurred tothe dimple or stake which makes this type restraining means unreliable.Moreover, under conventional practice, the cap well is not covered, andoccasionally, foreign substances such as dirt, sand or rock enter thewell and block the subsequent insertion of a blasting cap.

Accordingly, it is a principal object of the present invention toprovide an improved booster device wherein a blasting cap can beinserted into the cap well of the booster in a facile manner and whereinthe device is waterproof and wherein the cap well is shielded fromforeign substances prior to use. i

A further object of the invention is to provide sealing means for thebooster comprising a resilient member for reliably holding an insertedblasting cap in place.

Other objects of the invention will appear hereinafter, the novelfeatures and combinations being set forth in the appended claims.

Generally described, the present invention comprises a booster devicewhich is designed to receive a blasting cap and to hold said capsecurely therein, said device having in combination: an outer metalshell having a closed bottom and an open top; an inner metal shell ofsuflicient length and diameter to accommodate a blasting cap and of lesslength than the outer shell having a closed bottom and an open top andbeing coaxially disposed within said outer shell with the open topthereof positioned slightly below the top of the outer shell; a chargeof cap-sensitive explosive disposed within the annular and bottom spacebetween the outer shell and the inner shell to adjacent the top thereof;a resilient sealing member disposed over the charge and between theinner shell and the outer shell to the top thereof, said resilientsealing member having an overhanging lip in the top thereof with acentral opening of less diameter than the inner shell and having arupturable membrane beneath the overhanging lip, said membrane extendingover the top of the inner shell; and a crimp formed adjacent the top ofthe outer shell to compress the sealing member.

A preferred embodiment of the invention has been chosen for purposes ofillustration and description and is shown in the accompanying drawingsforming a part of the specification wherein reference symbols refer tolike parts Wherever they occur and wherein:

FIGURE 1 is a part elevational and part sectional view of a boosterdevice in accordance with the invention;

FIGURE 2 is a top plan view of the resilient sealing means for thebooster depicted in FIGURE 1; and

FIGURE 3 is an enlarged sectional view of the resilient sealing meansfor the booster taken along line 33 of FIGURE 2.

In FIGURE 1, an outer metal shell 10 has an inner metal shell 11coaxially disposed therein. The inner shell 11 is of less length thanthe outer shell 10 and is of sufiicient length and diameter to fullyaccommodate a conventional blasting cap which in respect to the devicedepicted is suitable for accommodating a No. 6 EB. cap. The open top ofthe inner shell 11 is positioned slightly below the top of the outershell 10. A charge 12 of crys talline high explosive such aspentaerythritol tetranitrate (PETN) is disposed within the bottom andthe annular space between the outer shell 10 and the inner shell 11 toadjacent the top thereof. A resilient sealing member 13 is disposed overthe charge 12 and between the inner shell 11 and the outer shell 10 tofit approximately flush with the top of the outer shell.

Referring now additionally to FIGURES 2 and 3, the resilient sealingmember 13 has a slotted overhanging lip 14 in the top thereof with acentral opening 15. The central opening 15 is of less diameter than theinner shell 11, and slots 16 and 17 together with a tapered edge 18 andrelief groove 19 at the top and immediately below the resilient lip 14,respectively, permit easy initial insertion of a blasting cap into theupper portion of the sealing mem ber 13. A rupturable membrane 20 ispositioned slightly below the relief groove 19 and extends over the topof the inner shell 11. This entire assembly comprising the resilientsealing member 13 is then compressed adjacent the top of the outer shell10 to compress the member therewithin and a permanent crimp 21 isthereby formed about the member.

The metallic shells for the device heretofore described were commercialbronze with the outer shell being 4 /2" L x /8" D crimped down to W Dand the inner shell 2 /8 L x 7 D. The sealing member was neoprene havinga durometer hardness of and extended into the outer shell %5. Thesealing member was molded as an integral piece with the rupturablemembrane having a thickness of 0.004". The explosive was PETN pressed toa density of about 1.45 g./cc. with a charge weight of 20 g. It will beunderstood that these dimensions and amounts are approximate and thatother materials may be used such as copper and aluminum for the shells,other cap-sensitive explosive such as cyclonite and tetryl, and otherpolymerization products of chlorophrene, Buna-S, reclaimed rubber andthe like. It has been found, however, with the elastomers that thedurometer hardness should be between about 70 and to give optimumresults for insertion of the cap into the booster well and its retentionafter insertion.

In utilizing the device, the bottom of a blasting cap is easily insertedinto the upper portion of the resilient sealing member due to thecombination of the tapered edge at the central opening, the slots andthe relief groove as hereinbefore described. As the cap is furtherinserted, the bottom thereof contacts the rupturable membrane and iseasily forced therethrough, and the cap is further advanced until it isfully seated Within the inner shell. In this position, as shown with thecap and leg wires out of function in FIGURE 1, the overhanging lip inthe top of the sealing member overhangs the top of the blasting cap withthe leg wires thereof extending up through the central opening. If anyaccidental pull is imparted to the leg wires tending to dislodge the capfrom the inner shell, the overhanging lip restrains the pullout movementof the cap and thereby keeps it reliably within the booster. The boosterdevices were field tested by shooting large containers filled withblasting composition insensitive to conventional blasting caps. Thelarge containers had a booster well therein to accommodate the boosterdevice entirely. Moreover, the booster devices were provided withadhesively aflixed plastic pull-out tabs. It is sometimes desired, atthe end of a days work, for example, to remove the device from its wellafter complete insertion. This is difficult to accomplish in the absenceof pull-out tabs since the device is entirely encased in its well. Itwas found that the objects of the invention were attained and that theshots were saisfactory in all respects.

Since further modification within the scope of the invention will beapparent to those in the art, it is intended that the invention belimited only by the appended claims.

What I claim and desire to protect by Letters Patent is:

1. A booster device which is designed to receive a blasting cap and tohold said cap securely therein, said device having in combination:

(a) an outer metal shell having a closed bottom and an open top;

(b) an inner metal shell of sufficient length and diameter toaccommodate a blasting cap and of less length than the outer shellhaving a closed bottom and an open top and being coaxially disposedwithin said outer shell wtih the open top thereof positioned slightlybelow the top of the outer shell;

(c) a charge of cap-sensitive explosive disposed within the annular andbottom space between the outer shell and the inner shell to adjacent thetop thereof;

(d) a resilient sealing member disposed over the charge and between theinner shell and the outer shell to the top thereof, said resilientsealing member having an overhanging lip in the top thereof with acentral opening of less diameter than the inner shell and having arupturable membrane beneath the overhanging lip, said membrane extendingover the top of the inner shell; and

(e) a crimp formed adjacent the top of the outer shell to compress thesealing member.

2. A booster device which is designed to receive a 4 blasting cap and tohold said cap securely therein, said device having in combination:

(a) an outer metal shell having a closed bottom and an open top;

(b) an inner metal shell of sufficient length and diameter toaccommodate a blasting cap and of less length than the outer shellhaving a closed bottom and an open top and being coaxially disposedwithin said outer :shell with the open top thereof positioned slightlybelow the top of the outer shell;

(c) a charge of cap-sensitive explosive disposed within the annular andbottom space between the outer shell and the inner shell to adjacent thetop thereof;

(d) a resilient sealing member disposed over the charge and between theinner shell and the outer shell to the top thereof, said resilientsealing member having a slotted overhanging lip in the top thereof witha tapered central opening of less diameter than the inner shell andhaving a relief groove and a rupturable membrane beneath the overhanginglip, said membrane extending over the top of the inner shell; and

(e) a crimp formed adjacent the top of the outer shell to compress thesealing member.

3. The booster device of claim 2 wherein the resilient sealing member isan elastomer having a durometer hardness of not more than 80.

4. The booster device of claim 2 wherein the resilient sealing member isa polymerization product of chlorophrene having a durometer hardness ofabout 75.

5. The booster device of claim 2 wherein the charge of cap-sensitiveexplosive is pentaerythritol tetranitrate.

References Cited by the Examiner UNITED STATES PATENTS 2,707,437 5/1955Noddin et al 10224 2,754,756 7/ 1956 Duesing 102-24 2,909,121 10/ 1959Gernert et al 102-24 3,150,590 9/1964 Silverman 10221.6 3,170,400 2/1965Nelson 102-24 BENJAMIN A. BORCHELT, Primary Examiner.

V. R. PENDERGRASS, Assistant Examiner.

1. A BOOSTER DEVICE WHICH IS DESIGNED TO RECEIVE A BLASTING CAP AND TOHOLD SAID CAP SECURELY THEREIN, SAID DEVICE HAVING IN COMBINATION: (A)AN OUTER METAL SHELL HAVING A CLOSED BOTTOM AND AN OPEN TOP; (B) ANINNER METAL SHELL OF SUFFICIENT LENGTH AND DIAMETER TO ACCOMMODATE ABLASTING CAP AND OF LESS LENGTH THAN THE OUTER SHELL HAVING A CLOSEDBOTTOM AND AN OPEN TOP AND BEING COAXIALLY DISPOSED WITHIN SAID OUTERSHELL WITH THE OPEN TOP THEREOF POSITIONED SLIGHTLY BELOW THE TOP OF THEOUTER SHELL; (C) A CHARGE OF CAP-SENSITIVE EXPLOSIVE DISPOSED WITHIN THEANNULAR AND BOTTOM SPACE BETWEEN THE OUTER SHELL AND THE INNER SHELL TOADJACENT THE TOP THEREOF; (D) A RESILIENT SEALING MEMBER DISPOSED OVERTHE CHARGE AND BETWEEN THE INNER SHELL AND THE OUTER SHELL TO THE TOPTHEREOF, SAID RESILIENT SEALING MEMBER HAVING AN OVERHANGING LIP IN THETOP THEREOF WITH A CENTRAL OPENING OF LESS DIAMETER THAN THE INNER SHELLAND HAVING A RUPTURABLE MEMBRANE BENEATH THE OVERHANGING LIP, SAIDMEMBRANE EXTENDING OVER THE TOP OF THE INNER SHELL; AND (E) A CRIMPFORMED ADJACENT THE TOP OF THE OUTER SHELL TO COMPRESS THE SEALINGMEMBER.